A method of controlling a differential lock. The differential lock is actuated to lock a differential assembly when wheel slip of a first wheel assembly is detected and a duration of the wheel slip exceeds a pre-activation buffer. The pre-activation buffer is based on acceleration of the first wheel assembly and vehicle speed.

A vehicle includes an engine, a primary axle drivably connected to the engine, and a secondary axle drivably connected to the engine by a clutch. A controller is programmed to, in response to map data indicating that the vehicle is off-road, enable an off-road transfer torque control mode in which temperatures of the clutch are compared to a lower threshold. The controller is further programmed to, in response to the temperature of the clutch exceeding the lower threshold, display a message to a driver indicative of rising temperatures of the clutch, and, in response to a temperature of the clutch exceeding an upper limit, enable a power limiting mode in which torque of the engine is limited to a predefined value.

Methods and systems for a differential assembly are provided herein. In one example, a diagnostic method includes generating a clutch fault according to a variance between an initial engagement position and a lock point position of a clutch motor that occur during engagement of an interaxle differential (IAD) locking clutch coupled to the clutch motor. In the IAD system, an actuation assembly is coupled to the clutch motor and the IAD locking clutch.

When temperature of a second power source of a vehicle becomes higher than a threshold value during a first mode in which three rotating elements of a differential gear can make differential movement and when four-wheel drive is needed, switching is performed to a second mode in which the three rotating elements are unified, and when four-wheel drive is not needed even when the temperature of the second power source becomes higher than the threshold value during the first mode, output of the second power source is restricted, while the first mode is maintained.

Methods and systems for a locking mechanism in an inter-axle differential are provided. A vehicle system, in one example, includes an electric motor coupled to a clutch assembly in a locking mechanism of an inter-axle differential coupled to a first axle and a second axle, the clutch assembly is configured to selectively disengage the locking mechanism, and in the disengaged configuration the locking mechanism permits speed differentiation between the first and second axles. The system further includes an electric motor brake coupled to the electric motor and configured to selectively apply a brake torque to the electric motor and the electric motor is configured to actuate the clutch assembly.

A vehicle power transfer unit assembly comprises an input shaft, an intermediate shaft at least partially surrounding the input shaft, a central shaft adjacent the input shaft, a peripheral shaft at least partially surrounding the central shaft, a first shift collar, and a second shift collar. The first shift collar is operable between a first position where torque is transferred from the input shaft to the intermediate shaft and a second position where torque is not transferred from the input shaft to the intermediate shaft. The second shift collar is operable between a third position where torque is transferred from the input shaft to the peripheral shaft and a fourth position where torque is transferred from the input shaft to the central shaft.

Methods and systems for improving traction and control of a tandem axle are described. In one example, a controller automatically locks an inter-axle differential so that traction of a vehicle may be improved. The approach may also include automatically locking one or more axle differentials in conjunction with locking of the inter-axle differential.

A vehicle includes a tandem axle system having an inter-axle differential and clutching assembly, a forward or first axle assembly, and a rear or second axle assembly. The inter-axle differential and clutching assembly includes a differential mechanism having first and second side gears and a clutch mechanism having a clutch member and an actuator assembly. At least one of the first axle assembly and the second axle assembly is in selective driving engagement with the inter-axle differential and clutching assembly.

Methods and systems for a locking mechanism in an inter-axle differential are provided. A vehicle system, in one example, includes an electric motor coupled to a clutch assembly in a locking mechanism of an inter-axle differential coupled to a first axle and a second axle, the clutch assembly is configured to selectively disengage the locking mechanism, and in the disengaged configuration the locking mechanism permits speed differentiation between the first and second axles. The system further includes an electric motor brake coupled to the electric motor and configured to selectively apply a brake torque to the electric motor and the electric motor is configured to actuate the clutch assembly.

Methods of controlling a tandem axle assembly in a vehicle, the tandem axle assembly including an inter-axle differential (IAD), one or more side gears, and a front tandem axle assembly having a pair of front tandem axle half shafts selectively connected to a pair of front tandem axle wheel hub assemblies. When a determined speed of the vehicle is greater or equal to a predetermined speed, the IAD may be locked, the tandem axle wheel hub assemblies may be disconnected from their respective tandem axle shafts, and/or the IAD may be moved out of engagement with the one or more side gears. When a determined speed of the vehicle is less than a predetermined speed, the IAD may be unlocked, the tandem axle wheel hub assemblies may be connected to their respective tandem axle shafts, and/or the IAD may be engaged with the one or more side gears.